The primary goal of this investigation is to examine the additive prophylactic potential of an individual psychotherapy based on interpersonal and social rhythm principles in bipolar I patients maintained on lithium carbonate. An adaptation of maintenance interpersonal psychotherapy, this intervention takes into account the specific vulnerabilities, symptoms, and interpersonal problem areas associated with bipolar disorder. Acutely ill patients in a manic or depressed episode are randomly assigned to either individual psychotherapy or medication clinic visits in addition to appropriate pharmacotherapy. Patients who stabilize (HRSD and Bech- Rafaelsen < 7 for four weeks) are then randomly assigned to preventative treatment with either individual psychotherapy or medication clinic visits in addition to pharmacotherapy. Thus, patients in this study will receive one of four possible treatment strategies: 1) preliminary phase psychotherapy followed by preventative phase psychotherapy; 2) preliminary phase medication clinic visits followed by preventative phase medication clinic visits; 3) preliminary phase psychotherapy followed by preventative phase medication clinic visit; or 4) preliminary phase medication clinic visits followed by preventative phase psychotherapy. Those patients who experience a relapse (during the initial twelve weeks of the preventative phase) or a recurrence (after week 12 of the preventative phase) will be treated with appropriate pharmacotherapy and continued in psychotherapy or medication clinic visits as dictated by their original randomization assignment. These patients will then be followed for the remainder of what would have been their time in the protocol had they remained well.